1. Field of the Invention
The present invention relates to a blue electroluminescent (EL) polymer, a method of preparing the blue EL polymer, and an organic EL device including the blue EL polymer, and more particularly, to a blue EL polymer, a method of preparing the blue EL polymer, and an organic EL device including the blue EL polymer with high color purity and color stability compared to a conventional blue EL polymer, the blue EL polymer being obtained by introducing an acridine derivative having a hole transporting ability to a polymer backbone.
2. Description of the Related Art
An organic electroluminescent (EL) device is an active matrix (AM) emissive display device using the principle that when current is applied to a fluorescent or phosphorescent organic compound thin layer (hereinafter referred to as ‘organic layer’), electrons and holes combine in the organic layer and thus light is generated. An organic EL device can be made light, is easy to manufacture because of simple elements thereof, and can provide a wide viewing angle of a high quality image. Also, the EL device can realize perfect mobile images and high color purity and can be obtained at low power and low voltage, and thus is appropriate for mobile electronic devices.
The organic EL devices can be classified into low molecular weight organic EL devices and polymer EL devices, depending on the material forming the organic layer.
In regard to the low molecular weight organic EL devices, which can be made by a vacuum deposition method, the light emitting material thereof can be easily purified, high purity can be easily obtained, and color pixels can be easily realized. However, despite the advantages of low molecular weight organic EL devices, improvements are still needed for practical application, for example, improvement of quantum efficiency and color purity and preventing the thin layers from being crystallized.
Meanwhile, polymer EL devices can be easily manufactured at low costs by forming an organic layer by spin coating or printing, and the mechanical characteristics of the organic layer is excellent. However, the polymer EL devices also have problems such as bad color purity, high turn-on voltage, low efficiency, and short lifetime, and at the present, studies are actively being conducted to find out ways to overcome these problems.